1. Field of the Invention
The present invention relates to a process for producing a high density ceramic of perovskite. Such a ceramic of perovskite is widely used in the field of functional ceramics such as piezo-electric elements, dielectrics, semiconductors, and optoelectronics materials.
2. Discussion of Background
Functional ceramics of perovskite are usually produced on an industrial scale by a so-called dry process wherein starting powder materials are mixed and calcined, and then the calcined powder mixture thus obtained is compacted and sintered. However, if the starting powder materials have no adequate powder characteristics, it is hardly possible to obtain a perovskite powder having excellent powder characteristics.
For instance, it is known that a starting zirconia powder is likely to coagulate, whereby it is difficult to obtain a perovskite powdered material having excellent powder characteristics i.e. a powder of a submicron level in a monodisperse state. When a perovskite powder were prepared from such a coagulated starting powdered material by the dry process, the average particle size of the perovskite powder would be at best about 2 .mu.m, and thus, it would be hardly possible to obtain the functional ceramics having a high density and excellent functionality by sintering the perovskite powder.
On the other hand, a readily sinterable perovskite powder of a submicron level may be obtained by a wet process such as an alkoxide method or a coprecipitation method. However, the wet process has such drawbacks that the cost is high and it involves operations which are complicated as compared with the dry process.